A record-breaking amount of sargassum, totaling 38 million tonnes, has accumulated across the Caribbean and adjacent regions in May, with even higher quantities anticipated for this month, according to a recent study. The brown, prickly seaweed is suffocating coastlines from Puerto Rico to Guyana and beyond, causing significant disruptions to tourism, harming wildlife, and even emitting toxic gases that led to the temporary closure of a school in Martinique due to health concerns.
This amount surpasses the previous record of 22 million tonnes set in June 2022, with the peaks of sargassum occurrence seemingly increasing every year. Despite the severity of the issue, the exact cause remains unknown, making it a topic of ongoing scientific investigation. Three types of sargassum are present in the Caribbean, and their proliferation is influenced by factors such as sunlight, nutrient levels, and water temperature, all of which are currently under study.
The influx of agricultural runoff, along with warming waters and changes in wind patterns, current, and rainfall, are also believed to contribute to the issue. While floating sargassum in the open ocean serves as a healthy ecosystem for various marine creatures, its presence near or on coastlines can have devastating effects. It can block sunlight essential for coral reefs, smother flora and fauna upon sinking, and once ashore, leads to the death of organisms within the seaweed which are then often scavenged by birds.
The economic and environmental impact on the Caribbean is significant, particularly for tourism-dependent islands where the seaweed can create foul smells and unsightly piles. Measures such as barriers to prevent beach accumulation and emergency cleanups have been implemented to address the issue. However, the high cost of specialized vessels and the care required to avoid disturbing sea turtle eggs pose significant challenges to mitigation efforts.
The situation is expected to worsen, with experts predicting even larger amounts of sargassum in June, calling for continued research and innovative solutions to address what has become a yearly crisis for the region.
Source: https://www.theguardian.com/world/2025/jun/03/caribbean-sargassum-seaweed
